diff --git a/gtk/gtktreemodelfilter.h b/gtk/gtktreemodelfilter.h
index 94d262dbe2..79e30fd31c 100644
--- a/gtk/gtktreemodelfilter.h
+++ b/gtk/gtktreemodelfilter.h
@@ -35,7 +35,7 @@ G_BEGIN_DECLS
 #define GTK_TREE_MODEL_FILTER_CLASS(vtable)     (G_TYPE_CHECK_CLASS_CAST ((vtable), GTK_TYPE_TREE_MODEL_FILTER, GtkTreeModelFilterClass))
 #define GTK_IS_TREE_MODEL_FILTER(obj)           (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GTK_TYPE_TREE_MODEL_FILTER))
 #define GTK_IS_TREE_MODEL_FILTER_CLASS(vtable)  (G_TYPE_CHECK_CLASS_TYPE ((vtable), GTK_TYPE_TREE_MODEL_FILTER))
-#define GTK_TREE_MODEL_FILTER_GET_CLASS(inst)   (G_TYPE_INSTANCE_GET_CLASS ((obj), GTK_TYPE_TREE_MODEL_FILTER, GtkTreeModelFilterClass))
+#define GTK_TREE_MODEL_FILTER_GET_CLASS(obj)   (G_TYPE_INSTANCE_GET_CLASS ((obj), GTK_TYPE_TREE_MODEL_FILTER, GtkTreeModelFilterClass))
 
 typedef gboolean (* GtkTreeModelFilterVisibleFunc) (GtkTreeModel *model,
                                                     GtkTreeIter  *iter,